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I got this info on how to test. My question concerns the sentence I highlighted in red .
Glow Plug Test
Set your DVOM to OHMS. Touch the red lead of your DVOM to the end of the glow plug where the electrical connector plugs ... JOIN NOW TO REMOVE TRACER

I got this info on how to test. My question concerns the sentence I highlighted in red.

Glow Plug Test
Set your DVOM to OHMS. Touch the red lead of your DVOM to the end of the glow plug where the electrical connector plugs into (not the end that sits inside the combustion chamber), and touch the black lead to the threaded part of the glow plug. You should obtain a reading of between 0.5 to 2.0 ohms on a "good" glow plug. Any higher than that, replace it. Also plan on replacing the glow plug harnesses too, since removal of them pretty much mandates replacement.

Okay, then the next step is to unplug the black connector plug (not the green one) from the glow plug controller on top of the passenger side valve cover. Look for a pink with light green stripe coloured wire in that connector. Use your DVOM with the red lead touching that cavity and the black lead touching your passenger side battery negative terminal. If you are still getting readings within 0.5 to 2.0 ohms, replace the GPCM. I have had more than my share of trucks flagging specific cylinder/circuit(s) faulty that ended up needing new GPCMs. If you are in doubt, "borrow" a known good GPCM from another truck, and re-run a self-test. By ohming out the circuit directly from the GPCM to the battery, you have eliminated the wiring from the GPCM all the way to the glow plug, leaving the GPCM the only possible component left to set the DTC.

Is that statement correct even though the same reading indicates a good glowplug?

What about when you plug it in? Does it start better after being plugged in?

Hard to say man, the glow plug systems on these rarely go bad, but it is possible. I would probably test the glow plugs before replacing anything. Have you tried getting the codes read? I know the glow plugs will throw a soft code, meaning it wont trip the check engine light, but you might still have a code there.

Glow Plug Test
Set your DVOM to OHMS. Touch the red lead of your DVOM to the end of the glow plug where the electrical connector plugs into (not the end that sits inside the combustion chamber), and touch the black lead to the threaded part of the glow plug. You should obtain a reading of between 0.5 to 2.0 ohms on a "good" glow plug. Any higher than that, replace it.

Also plan on replacing the glow plug harnesses too, since removal of them pretty much mandates replacement.

A few questions
1. To do the above test procedure does the glowplug get taken out to test it or remain in the engine and you just touch the top of the threaded area?

2. Has anybody been able to reuse the wiring harness or does it just make sense to plan on spending the $150.00 or so and replace them?

3. They make a tool to pop the connectors off - is it worth getting and if so where would you find one? I went to the local dealer and he told me to check with AutoZone or somebody like that. Stopped at a CarQuest and they say it is available from a dealer only.

4. If the glowplugs need replacing would Ford ones be best or is there a better after market brand?

One thing I have found with the PSD the more I learn the more I realize I don't know

Since I'm not afraid to ask a seemingly stupid question, here's one: Are the glow plugs on when the motor is running? It had enough temp to blow warm air out the heater. I just had my alternator load tested (been seeing the batt light this week) and the results said loosely: If glow plugs on turn off, if glow plugs are off, fault with charging system.

I'm giong to remove the alternator Saturday and have it spun, but it seems a good time to get spooled up o nhow/when glow plugs work. Probably is the alt since I am trying to save money to go for a trip soon.

A few questions
1. To do the above test procedure does the glowplug get taken out to test it or remain in the engine and you just touch the top of the threaded area?

You should be able to do it with them still in the truck...

2. Has anybody been able to reuse the wiring harness or does it just make sense to plan on spending the $150.00 or so and replace them?

I've heard if you have to replace all of them, just plan on getting the wiring harness. The only good way I know of to remove the harness without destroying it is to remove the rocker box with it still attached and push it out from the inside. If you only have one glowplug to replace, then I would try and not break it as best as possible, you can probably get away with just one.

3. They make a tool to pop the connectors off - is it worth getting and if so where would you find one? I went to the local dealer and he told me to check with AutoZone or somebody like that. Stopped at a CarQuest and they say it is available from a dealer only.

I'm fairly certain it's dealer only, but from what I've read it doesn't exactly work great anyways.

4. If the glowplugs need replacing would Ford ones be best or is there a better after market brand?
Definitely motorcraft. You can get all 8 for under $100, I think it's like $70-$80.

One thing I have found with the PSD the more I learn the more I realize I don't know

Answers in RED above

Originally Posted by Karls03

Since I'm not afraid to ask a seemingly stupid question, here's one: Are the glow plugs on when the motor is running? It had enough temp to blow warm air out the heater. I just had my alternator load tested (been seeing the batt light this week) and the results said loosely: If glow plugs on turn off, if glow plugs are off, fault with charging system.

I'm giong to remove the alternator Saturday and have it spun, but it seems a good time to get spooled up o nhow/when glow plugs work. Probably is the alt since I am trying to save money to go for a trip soon.

Karl, The glow plugs are only on at certain times, but typically when you first start the truck they are on when it's running yes. They stay on for something like 120seconds. Let me see what I can find, I know there are parameters it follows regarding intake air temp, and possibly oil temp and a few others, as well as time.